Story: Bats

Few people will have seen New Zealand’s thumb-sized native bats – the country’s only native land mammals. In pre-human times, they darted about the forests in their millions, but today they are reduced to a few scattered groups. We are only now beginning to learn more about these tiny creatures of the night.

Full story by Veronika Meduna

Main image: Short-tailed bat

The Short Story

A quick, easy summary

There are only two land mammals native to New Zealand, and they are both bats – the long-tailed bat and the lesser short-tailed bat. The Māori name for both species is pekapeka.

Size and age

New Zealand’s bats have bodies the size of your thumb (5–6 centimetres from nose to tail), and their wingspan is nearly 30 centimetres.

Nobody knows for sure how long they live – it may be as much as 30 years.

Habitat

The bats live in native forests throughout New Zealand. They roost in large, hollow trees and the occasional cave, sometimes alone and sometimes in colonies (groups) of up to 100 bats.

Flight

New Zealand bats are expert fliers. They have long finger bones joined by thin layers of tissue (membranes), forming wings. Lesser short-tailed bats have been clocked at speeds of up to 60 kilometres per hour.

Echolocation

When hunting for food and finding their way, bats use echolocation. They send out high-frequency sounds, too high for human hearing. Then they listen for the echoes that bounce back off surrounding objects. The echoes tell the bat about the location, size and identity of the objects around them.

Torpor and hibernation

Bats can have times of torpor (non-movement) to save their energy. The bat becomes motionless, and its temperature drops to match the temperature around it. In winter they hibernate, with long periods of torpor (6–10 days) and short bursts of activity (anywhere between a few hours and a few days).

Lesser short-tailed bats

Lesser short-tailed bats are solid little animals with pale grey-brown fur, long pointed ears and a stumpy tail. They are the only bat species that hunts for food on the ground – their wings fold away under side-flaps of skin, and they use the elbow parts of the wings as front legs. They are nocturnal (active at night). Their diet includes insects, fruit, pollen, seeds and nectar.

Long-tailed bats

Long-tailed bats have chocolate-brown fur, short ears, and a long tail completely enclosed within a thin membrane attached to its legs. They are more common than lesser short-tailed bats, but are rarely seen. They are active both at dusk and into the night, and eat only flying insects.

Survival

The arrival of humans had a major effect on New Zealand bats and both species are now under threat. The Department of Conservation is working to protect both New Zealand bat species.